Imagine floating on the empty blue Pacific Ocean, nothing but water in every direction, sunrise to sunset. Yet under the surface swim thousands of great white sharks.
That’s not a bad dream — it’s actually what happens around this time of year several thousand miles off the coast of Baja California, about halfway to Hawaii. The king predators congregate in a huge area of the ocean affectionately named the White Shark Cafe.
But why the big sharks stack up in this remote spot remains a mystery. The area is also known as “the desert of the ocean” and so far Sal Jorgensen, a research scientist at the Monterey Bay Aquarium, says there is little observable life to sustain a food chain. The sharks also assume bizarre behavior, sometimes diving thousands of feet at intervals as short as ten minutes apart. The reason white sharks travel halfway across the ocean appears to be somewhere between eating and meeting a mate, hence the idea of a “cafe” — but only better research can determine whether it’s more “restaurant” or “motel.”
“We know very little,” Jorgensen says, joking that it seems like Burning Man for white sharks.
Scientists know so much about what’s happening above the surface of the water, but due to a lack of sensory equipment, they know comparatively little about what’s going on below. Most data for studying sharks, or any ocean phenomenon, is gathered via buoy (which are immobile), satellite (inexact, usually confined to surface measurement and not always in range) or scientists on a ship (time consuming and expensive). When predicting the weather on land, meteorologists can lean on countless weather stations to gather data and generate the forecast.
“We have nothing like that,” Florida State University oceanographer Ian MacDonald says, noting there are only about a dozen data gathering buoys in all of the Gulf of Mexico. His group has been trying to study the effect of the Deepwater Horizon oil spill on the ocean surface, a critical interface for atmospheric changes, and how it has altered phytoplankton growth. “As a consequence we’re always playing catchup.”
This is where drones come in. Autonomous craft are reshaping the way scientists study the ocean and two local bay area companies, Liquid Robotics and upstart Saildrone, funded by the Marine Science and Technology Foundation (founded by Google chairman Eric Schmidt), have been making waves with their unmanned gliders and sailboats. Saildrone recently completed a voyage around Hawaii and back to the Bay Area with its autonomous sailboats. But now the group must prove its crafts can do more than simply get from point A to point B — like gather critical ocean data.
Sensor for picking up acoustic transponders on great white sharks.
“The next stage is to demonstrate that we can do real, valuable science,” says Saildrone lead researcher Richard Jenkins.
When I visited Saildrone’s workshop in a hanger on Alameda’s old Naval base, Jenkins showed off the shark sensors, which attach to the craft’s keel. Getting sensors under ocean surface is key. The idea is that as the saildrone passes within range of the shark, the sensor picks up on-animal acoustic tags and beams the data back to mission control. To date, researchers have to wait until the tag pops off (usually about a year) and then retrieve it via ship, which can cost tens of thousands of dollars per day. Then researchers must assemble the animal’s activities retroactively.
The hope is that with drones periodically sending that data home as they traverse the White Shark Cafe or any other area of interest, observations occur in real time — at far less expense. Jorgensen and distinguished Stanford marine biologist Barbara Block, who is working with Liquid Robotics and Saildrone to prove their crafts’ worth, hope for better in situ data such as the animal’s exact positions in the water column at certain moments, giving them a 3-d perspective. This indicates whether (or what) the sharks are hunting, potentially helping scientists understand the purpose of the Cafe, not to mention other migratory and feeding habits. Block hopes for similar discovers with bluefin tuna and other pelagic fish, which habitat the open ocean away from shore and sea floor.
“You’d think we know, but we don’t,” she says. “It’s a very inaccessible world.”
The Stanford group has tried to open some of that world to the public with the Shark Net app for iPhones, which lets anyone monitor and see pictures of tagged fish, but continuous information is tricky. “This is a great concept, but the data is not up-to-date,” notes a top comment in the iTunes Store. “Would be a great app if it was kept current.”
Here are the recreated journeys of two white sharks tagged off California by Stanford researchers. The left-hand fish goes to Hawaii and back. The right-hand fish visits the Cafe.
But even if the information is current, Saildrone must still prove its instrumentation provides accurate numbers when measuring other data points like ocean salinity or temperature. The marine environment is brutal and enough battering, heat and cold can warp calibration. Jenkins and company are working with NOAA to fine-tune the sensors. Even a slight deviation can make an entire dataset meaningless.
“Just because you collect a number, doesn’t mean it’s right,” Jenkins says.
FSU’s MacDonald hopes the drones will provide the data to better predict tropical storms. Right now he says satellites can only measure surface temperatures but measuring subsurface is also key. That’s where a fleet of unmanned vehicles would start providing better info. “Anything that will give us a better handle would be very important,” he says.
And drones could also map areas previously tricky for ships to pass. Saildrone’s crafts only cuts six feet under the water, so it can navigate shallow areas — meaning it could take far more nuanced pictures of the ocean floor and save on the fuel for ships performing the task today.
The saildrones cost almost nothing to operate and are relatively simply to control and monitor. Provide destination coordinates and off it goes — the command software is simple enough to run in a web browser and Jenkins occasionally monitors the craft from his iPhone (via a private website). The vessel has small solar panels to power the onboard computers and sensors, but the drone moves completely on wind power.
But the drones can’t stay at sea forever. Despite protective paint and a streamlined design, algae and other sea life will eventually coat the craft and slow it down, meaning it has to come back to shore for a clean and tune up.
The saildrone’s hull is shaped something like a big pelagic fish, but Jenkins said sharks haven’t mistaken it for prey yet. In fact, he says when they’ve sailed the craft near areas populated with birds, seals or other marine life, they don’t make much fuss — but a craft with an engine usually has them scrambling to get away. His theory is that because the drones are silent and without vibrations, the animals don’t pay much mind, like a piece of fast-moving driftwood. (Block said Liquid Robotics hadn’t had an issue with shark attacks either.)
A recovered acoustic sensor on a great white shark. (Monterey Bay Aquarium)
This sort of detailed insight into the lives of sharks and large pelagics presents something of a double-edged sword. Researchers need to publish data so activists and governments know where to establish marine conservation zones. But that data also informs fisherman, many of whom disregard catch limits on threatened species or even brutalize animals, like slicing off shark fins for soup and leaving them to die.
“We’re always faced with this dilemma,” says Jorgensen.
Yet to add one more bullet to the list of tasks these sea-faring drones could perform, Jenkins has worked with government agencies to test saildrones for patroling protected fisheries and taking pictures of boats violating the rules. Those discussions are also in very early stages — like the other marine applications for unmanned crafts.
Drones haven’t proven to be a panacea for answering marine science questions quite yet. But Block is hopeful.
“These are the modern generation tools to study the ocean,” she says.
SF Gate: http://blog.sfgate.com/techchron/2014/02/27/tracking-great-white-sharks-with-drones-right-from-an-iphone/#21057101=0